In the related art, an LED illumination unit 214 as shown in FIG. 9 was used (see PTL 1) a lamp, an indicator for a motor vehicle or the like. The LED illumination unit 214 is constituted by an LED 16, a substrate 17 with the LED 16 mounted thereon, an LED illumination housing 215 (hereinafter, referred to as a housing) that accommodates the LED 16 and the substrate 17 or the like. Furthermore, reference numeral 18 of FIG. 9 is an electric wire that is connected to the substrate 17.
The housing 215 is molded by an injection molding machine 201 shown in FIGS. 6 to 8, and is formed of a transparent thermoplastic resin. As shown in FIG. 9, the housing 215 includes a bottom wall 215a having a flat surface, a peripheral wall 215b that is erected from a periphery of the bottom wall 215a in a cylindrical shape, and a flange portion 215c that is provided in an end portion of the peripheral wall 215b. Furthermore, the LED 16 emits light beyond the bottom wall 215a. 
As shown in FIG. 6, the injection molding machine 201 includes a fixing mold 202, a moving mold 3 that is fitted to the fixing mold 202, a driving mechanism 6 that brings the moving mold 3 into contact with the fixing mold 202 and separates the moving mold 3 from the fixing mold 202, and a material supply mechanism 10 that injects resin of a molten state into a cavity 212 which is configured when the fixing mold 202 and the moving mold 3 are fitted to each other. Furthermore, reference numeral 11 in FIG. 6 indicates a mold mating surface between the fixing mold 202 and the moving mold 3, that is, a parting line.
The fixing mold 202 is formed in a U-shaped cross section that has a cavity formed in a concave shape from the parting line 11. An inner surface shape of the cavity of the fixing mold 202 is transferred onto resin, whereby the fixing mold 202 forms an external form of a housing 215. Furthermore, on a bottom surface 220 of the fixing mold 202, a gate hole communicating with a runner 7 of the material supply mechanism 10 is provided.
The moving mold 3 includes a core portion 30 that is formed in a convex shape from the parting line 11. The core portion 30 is situated in the cavity of the fixing mold 202 and forms a portion that is a hollow of the housing 215.
As shown in FIG. 6, the driving mechanism 6 is constituted by a support member 4 with the moving mold 3 attached thereto, a hydraulic cylinder device that is connected to the support member 4 or the like. The hydraulic cylinder device includes a rod 5 that is moved forward and backward along an arrow X direction in the state in which the support member 4 is attached to a tip thereof.
The material supply mechanism 10 is constituted by a heating cylinder 9 that heats and melts a pallet-like resin, an injection nozzle 8 that injects resin molten in the heating cylinder 9, and a runner 7 that leads resin injected from the injection nozzle 8 into each cavity 212 of a plurality of molds or the like.
In the injection molding machine 201 mentioned above, the housing 215 is formed as described below. Firstly, as shown in FIG. 7, in the state in which the fixing mold 202 and the moving mold 3 are fitted to each other and the mold is closed, resin of the molten state is injected into the cavity 212 by the material supply mechanism 10. Next, a predetermined time elapses in the state in which the fixing mold 202 and the moving mold 3 are fitted to each other, whereby resin in the cavity 212 is cooled by the mold and is gradually hardened. After that, as shown in FIG. 8, the moving mold 3 is separated from the fixing mold 202, the mold is opened, and the molded housing 215 is pulled out. In this manner, the housing 215 shown in FIG. 9 is molded.